Ignition system for rotary internal combustion engine

ABSTRACT

The system includes a battery connected through an ignition switch to two ignition coils, each including a primary winding and a secondary winding. Each of the primary windings is connected to its associated breaker which is operated in the usual way by a cam driven by the engine drive shaft. The secondary windings are selectively connectable to a spark plug by a distributor. Switch means are interposed between the ignition switch and one of the ignition coils to open the circuit therebetween in response to deceleration or idling operation of the engine, thereby causing the spark plug to be fired in alternate order. By so doing, the engine is forcibly fired in alternate order, whereby roughness in power output caused by misfire is eliminated.

United States Patent 91 Kishimoto et a1.

IGNITION SYSTEM FOR ROTARY INTERNAL COMBUSTION ENGINE Inventors: Kyuji Kishimoto; Toshiaki Tojima;

Hideto Ishii, all of Tokyo, Japan Assignee: Nissan Motor Company, Limited,

Yokohama, Japan Filed: Oct. 3, 1972 Appl. No.: 294,585

Foreign Application Priority Data Oct. 7, 1971 Japan 46-78998 US. Cl. l23/8.09, 123/97 B, 123/117 R, 123/198 F Int. Cl. F02b 5/04 Field of Search 123/148 E, 117 R, 117 A, 123/8.09,198 F, 97 B References Cited UNITED STATES PATENTS Heidner 123/198 F Mar. 4, 1975 3,703,887 11/1972 Panhard 123/117 R 3,716,991 2/1973 Tatsutomi 123/117 R 3,735,739 5/1973 Panhard 123/117 R Primary Examiner-Charles J. Myhre Assistant Examiner-Ronald B. Cox

1571 ABSTRACT The system includes a battery connected through an ignition switch to two ignition coils, each including a primary winding and a secondary winding. Each of the primary windings is connected to its associated breaker which is operated in the usual way by a cam driven by the engine drive shaft. The secondary windings are selectively connectable to a spark plug by a distributor. Switch means are interposed between the ignition switch and one of the ignition coils to open the circuit therebetween in response to deceleration or idling operation of the engine, thereby causing the spark plug to be fired in alternate order. By so doing, the engine is forcibly tired in alternate order, whereby roughness in power output caused by misfire is eliminated.

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IGNITION SYSTEM FOR ROTARY INTERNAL COMBUSTION ENGINE This invention relates to ignition systems for internal combustion engines and, more particularly, to an ignition system for a rotary internal combustion engine which functions to eliminate the roughness of power output caused by a misfire during deceleration or idling. Generally, the invention contemplates an ignition system incorporating switch means operable in response to deceleration or idling for causing-a spark plug to be fired in alternate order to produce smooth operation of the engine. A V V In the operation of a rotary internal combustion engine, it has been found that during rotation of the polygonal rotor, overlapping takes place in which the inlet ,port communicates with the outlet port due to its inherent construction. In this condition, a portion of the exhaust gases is sucked into the suction chamber and is mixed with a fresh air-fuel mixture, which causes a misfire or incomplete combustion of the mixture, especially at deceleration or idling, i.e., when the pressure in the operating chambers of the engine is extremely low. A rotary engine with a relatively long overlapping period has a greater tendency to misfire; however, even an engine with no overlapping period fails to avoid a misfire, because even the minimum volume of exhaust gases remaining in the operating chambers adversely effect complete combustion of the subsequently intro- Once a misfire occurs, the unburned mixture remaining in the combustion chamber is again sucked into theoperating chamber tends to alternate between a fire and a misfire.

Shown below is a table illustrating the manner of operation of a wankel type rotary engine, in which each of the three operating chambers A, B and C alternate between a tire indicated at 0 and a misfire at X.

As will be apparent, it is most probable that the three operating chambers consecutively misfire after the consecutive firing of them. When this occurs, the engine tends to be thrown out of balance so that shaking of the car results because of the vibration of the engine is in resonance with its inherent vibration and such accumulated vibration istransmitted through the engine output shaft and the transmission to the real wheels of the vehicle and thus to the vehicle carrier. Such shaking of the car takes place especially when the rotor speed is reduced from 2,000 to 1,500 rpm. However, if the alternation between a tire and a misfire occurs in the manner as indicated at Nos. 4 and 8, the roughness n spwsrpi trzqt se ted; t

It is, therefore, an object of the present invention to provide an improved ignition system for an internal combustion rotary enging which functions, during deceleration or idling, to cause a spark plug to be fired in alternate order so as to eliminate the roughness in .HL wk wmw Another object of the present invention is to provide an improved ignition system which is specifically des a sdiqr wa ery ir rItalianbust ttsrsiue- In order to achieve these objects, the present invention proposes to provide an ignition system including a battery connected through an ignition switch to at least one ignition coil, including a primary winding and a secondary winding. The at least one primary winding is connected to its associated breaker which is operated in the usual way by a cam carried on a cam shaft which 1 in turn is driven by the engine output shaft. The at least Operatl" l H I"'"1 l' 1 ing ABC ABC ABC ABC A Proba- Chambility bers No.

0 X 0 X 0 l O X 0 X /s Three 0 X 0 X consecutive O X 0 X 0 firings 2 O X 0 X A; followed by X 0 X 0 three con- 0 X 0 X 0 secutive 3 X 0 X 0 Vs misfires X 0 X 0 a O X 0 X 0 4 X 0 X 0 A;

O X 0 X X 0 X 0 X 5 X 0 X 0 Three X 0 X 0 consecutive X 0 X 0 X firings 6 X 0 X 0 is followed by O X 0 X three con- X 0 X 0 X secutive 7 O X 0 X A; misfires O X 0 X X 0 X 0 X 8 O X 0 X 3 one secondary winding is selectively connectable to a spark plug by a distributor mounted on the cam shaft. Also included in the ignition system is switch means interposed between the ignition switch and the at least one ignition coil, which operates to open the ignition circuit associated with the particular ignition coil during deceleration or idling, thereby causing the spark plug to be fired in alternate order. By so doing, the engine is forcibly fired in alternate order, whereby roughness in power output is eliminated.

These and other objects will be apparent from the following description of embodiments of the invention when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a circuit diagram of an ignition system according to a preferred embodiment of the invention;

FIG. 2 is a modification of the ignition system shown in FIG. 1; and

FIG. 3 is another modification of the present tion.

Referring now to FIG. 1, there is shown an ignition system of the present invention which is specifically designed for a rotary internal combustion engine of the epitrochoidal type, generally designated by reference numeral 10. The internal combustion engine l is shown to include a housing 11 having an epitrochoidal inner surface 12, an inlet port 13 and an outlet or exhaust port 14. Lateral walls 15 (only one of which is shown in FIG. 1) are provided to complete the housing. A drive shaft 16 extends between and through the end walls 15 and carries an eccentric portion 17 on which is rotatably mounted a generally trigonal rotor 18 having three apex portions 19, 20 and 21 with convexly arcuate working surfaces 22 extending between adjacent apex portions. It should be noted that an apex seal member to be mounted in a groove at each apex of the rotor is herein omitted for the sake of simplicity of illustration. Indicated at 25 is a spark plug which ignites a combustible air-fuel mixture supplied into the housing chamber.

The ignition system, as is conventional, includes a dc. voltage source or battery connected through an ignition switch 31 to two ignition coils 32 and 33, each including primary windings 35 and 36 and secondary windings 38 and 39. The secondary windings 38 and 39 are respectively connected to rotary electrodes 41 and 42 of a distributor 43. Respectively connected to each of the primary windings 35 and 36 are breakers 45 and 46, which breakers are caused to open and close by rotation of a cam 48 carried on a cam shaft indicated diagrammatically at 49. The cam 48 includes opposed lobes 51 arranged for successively engaging the operating pawls 53 and 54 of the respective breakers 45 and 46, As is usual, condensers 56 and 57 are respectively connected in parallel with the breakers 45 and 46.

The rotary electrodes 41 and 42 of the distributor 43 are carried on a rotor 59 mounted on the cam shaft 49 for rotation at one half drive shaft speed. The rotary electrodes 41 and 42 are, as shown, angularly spaced by 180 and electrically insulated from each other. The distributor 43 also includes stationary electrodes 61 and 62 which are also 180 spaced from each other and adpated to be successively contacted by the rotary electrodes 41 and 42 as the rotor 59 rotates. One of the stationary electrodes 61 and 62 is connected through a conductor 63 to the spark plug 25 and the other thereof is grounded. Thus, it will be understood that the inven-.

secondary windings 38 and39 are selectively connectable to the spark plug 25 by the distributor 43.

'- Interposed between the ignition coil 33 and the ignition switch 31 is a normally closed, pneumatically controlled switch means 65 which operates to open the circuit between the ignition coil 33 and the ignition switch 31' when the vacuum in the intake manifold 66 rises above a predetermined value, as in the case of deceleration. The switch means 65 can be operated by a diaphragm unit 68 through a mechanical linkage 69, which diaphragm unit communicates through a conduit 70 with the intake manifold 66 downstream of the throttle valve 71. Although not shown, a spring member is operatively associated with the switch means 65 or the mechanical linkage 69 so as to normally retain the switch means 65 in the closed position. When the vacuum in the intake manifold 66 exceeds a predetermined value, a diaphragm (not numbered) of the diaphragm unit 68 moves the mechanical linkage 69 to the right-hand direction as viewed in FIG. 1, causing the switch means 65 to open. Thus, further opening of the breaker 46 by the cam'48 does not result in firing of the spark plug 25, while the spark plug 25 is fired in response to opening of the breaker 45 by the cam 48. By so doing, it will be understood that firing of the spark plug 25 is effected in alternate order, as in the cases of Nos. 4 and 8 shown in the above table, so that the engine is forcibly fired in alternate order. While, in this embodiment, the normally closed, pneumatically controlled switch means 65 is shown as being located between the ignition coil 33 and the ignition switch 31, it is to be understood that the switch means 65 could as well be provided between the ignition coil 33 and the breaker 46 or between the ignition coil 33 and the distributor 43.

Referring to FIG. 2, there is shown another embodiment of the present invention which is identical to that shown in FIG. 1 except that the switch means 65 is replaced by two switch means and 81 connected in parallel with each other.

The switch means 80 is of a normally closed type and is operatively connected to the throttle valve 71' through a mechanical linkage 81' so as to be opened only when the throttle opening is of such a value as when the engine is idling. Alternatively, the switch means 80 may be operated by a mechanical linkage (not shown) connecting the accelerator pedal and the throttle valve.

The switch means 81 is also of the normally closed type and can be actuated by a solenoid 83 to open the circuit between the ignition coil 33' and the ignition switch 31' when engine speed exceeds a predetermined value. Specifically, one end of the solenoid 83 is connected through the ignition switch 31' to the battery 30' and the other-thereof is connected through a relay switch 85 to ground. The relay switch 85 is normally open and can be closed by an electromagnet 87 to energize the solenoid 83 thereby to open the switch 81. The electromagnet 87 is connected at one end to the ground and at the other to a conventional magneto 89 which is driven by the main shaft 16' of the rotary engine. The relay switch 85 is so adjusted as to close the solenoid circuit when the engine speed exceeds a certain predetermined value which is relatively high.

With the parallel connection of the switch means 80 and 81 shown in FIG. 2, firing of the spark plug 25 in alternate order can be accomplished only when the two switch means 80 and 81 are simultaneously opened, i.e., when the throttle valve 71' is closed while simultaneously the vehicle is operating at a high speed but decelerating at the same time. If the engine speed is below the predetermined value, opening of the switch 80 caused by closure of the throttle valve 71' does not result in firing of the spark plug 25 in an alternate order.

Although, in this embodiment, a combination of an electromagnet 87 and a magneto 89 is employed to open the switch 81 at high engine speed, it is to be understood that the swtich 81 can be equally operated by some means utilizing centrifugal force.

Referring to FIG. 3, there is shown a modification of the present invention which is different from those shown in FlGS. 1 and 2 in that a single ignition coil is employed.

As shown, the ignition system comprises conventionally a battery 92, an ignition switch 93, and an ignition coil 94 including a primary winding 95 and a secondary winding 96. The primary winding 95 is connected to a breaker 98, and the secondary winding 96 is selectively connectable to a spark plug indicated diagrammatically at 99, through a distributor 101. The breaker 98 is operated in the usual way by a cam 103 carried on cam shaft 104 which is driven by the engine drive shaft (not shown) at one half of the drive shaft speed. In the case of a three chamber rotary internal combustion engine, the cam 103 includes opposed lobes 106 for successively opening the breaker 98 as the cam shaft 104 rotates. A condenser 118 is connected in parallel with the breaker 98. As is common practice, operation of the distributor 101 and opening of the breaker 98 are coordinated so that the spark plug 99 is fired in sequences of 180 intervals relative to rotation of the cam shaft 104.

The ignition system also includes switch means 110 provided between the ignition switch 93 and the ignition coil 94-, and an auxiliary breaker 112 connected in parallel with the switch means 110. The switch means 110, being similar to switch means 65, 80 and 81 shown in FIGS. 1 and 2, is normally closed and operates to open the circuit between the ignition switch 93 and the ignition coil 94, when a sensor 120 senses a decelerating or idling condition of the engine. The sensor 120 may be of any construction as long as it senses a decelerating or idling condition of the engine. The auxiliary breaker 112 is operated by a cam 115 having a single lobe 116, the cam 115 also being carried on the breaker cam shaft 104.

With this arrangement, if the engine is in normal operating condition, the spark plug 99 is tired in sequences of 1 80 intervals relative to rotation of the cam shaft 104, since the switch means 110 remains closed, connecting the ignition coil 94 directly to the ignition switch 93. in this condition, opening of the auxiliary breaker 112 does not affect firing of the spark plug 99. If, on the other hand, the vehicle starts decelerating, causing the switch means 1 to open, the ignition coil 94 is connected to the battery 92 only when the auxiliary breaker 112 is closed. Since, as described above, the single lobe 116 of the auxiliary breaker cam 115 is angularly aligned with one of the opposed lobes 106, firing of the spark plug 99 at 360 intervals results, which means that the spark plug 99 is fired in alternate order. When this occurs, the engine is forcibly tired in alternate order, so that the roughness of power output is eliminated.

Although the ignition systems for a rotary internal combustion engine have been shown with one or more mechanical breakers, other types of breakers, such as those employing transistors or thyristors as switching elements can also be used. Furthermore, the disclosed arrangement can be adapted for use with ordinary twoor four-stroke piston engines.

What is claimed is:

1. In an ignition system for a rotary internal combustion engine including an ignition switch, two ignition coils each having a primary winding and a secondary winding, two breakers each connected to the respective primary winding of each of the ignition coils, a spark plug for normally igniting a combustible air-fuel mixture in each consecutive compression chamber of the engine, a distributor for selectively connecting the secondary windings of the ignition coils to the spark plug to cause a spark to be incident to the opening of the breakers, and cams driven by the engine for opening the breakers, the improvement comprising an electromechanical switch member connected between one of the ignition coils and the ignition switch and responding to deceleration and idling conditions of the engine for controlling the firing of the spark plug to produce a spark in alternate compression cycles, in which the electromechanical switch member for controlling the firing of the spark plug comprises a first normally closed switch connected between the ignition switch and one of the ignition coils, and a second normally closed switch connected in parallel with the first switch, the first switch being opened when the degree of throttle opening is of such a value as when the engine is idling, the second switch being opened when engine speed exceeds a predetermined value.

2. An ignition system as claimed in claim 1, in which the first switch is operatively connected through a mechanical linkage with the throttle valve.

3. An ignition system as claimed in claim 1, in which the second switch is opened by a solenoid which is actuated by a relay switch, the relay switch being closed by an electromagnet connected to a magneto which is driven by the engine drive shaft.

4. in an ignition system for a rotary internal combustion engine including an ignition switch, an ignition coil having a primary winding and a secondary winding, a breaker connected to the primary winding of the ignition coil, a spark plug for normally igniting a combustible air-fuel mixture in each consecutive compression chamber of the engine, a distributor for selectively connecting the secondary winding of the ignition coil to the spark plug to cause the production of spark at the spark plug to be incident to the opening of the breaker, and cams driven by the engine for opening the breaker, the improvement comprising an electromechanical switch member connected between the ignition coil and the breaker and responsive to certain decelerating and idling conditions of engine for controlling the firing of the spark plug to produce a spark in alternate compression cycles, in which the electromechanical switch member for controlling the firing of the spark plug comprises a normally closed switch connected between the ignition coil and the ignition switch, the switch being opened in response to engine decleration, an auxiliary breaker connected in parallel with the switch, and a cam driven by the engine for opening the auxiliary breaker in alternate openings of the breaker, in which the cam for opening the breaker is a cam having two opposed lobes, and the cam for opening the auxiliary breaker is a cam having a single lobe, the single lobe being angularly aligned with the opposed lobes of the breaker cam.

a s: a 

1. In an ignition system for a rotary internal combustion engine including an ignition switch, two ignition coils each having a primary winding and a secondary winding, two breakers each connected to the respective primary winding of each of the ignition coils, a spark plug for normally igniting a combustible air-fuel mixture in each consecutive compression chamber of the engine, a distributor for selectively connecting the secondary windings of the ignition coils to the spark plug to cause a spark to be incident to the opening of the breakers, and cams driven by the engine for opening the breakers, the improvement comprising an electromechanical switch member connected between one of the ignition coils and the ignition switch and responding to deceleration and idling conditions of the engine for controlling the firing of the spark plug to produce a spark in alternate compression cycles, in which the electromechanical switch member for controlling the firing of the spark plug comprises a first normally closed switch connected between the ignition switch and one of the ignition coils, and a second normally closed switch connected in parallel with the first switch, the first switch being opened when the degree of throttle opening is of such a value as when the engine is idling, the second switch being opened when engine speed exceeds a predetermined value.
 2. An ignition system as claimed in claim 1, in which the first switch is operatively connected through a mechanical linkage with the throttle valve.
 3. An ignition system as claimed in claim 1, in which the second switch is opened by a solenoid which is actuated by a relay switch, the relay switch being closed by an electromagnet connected to a magneto which is driven by the engine drive shaft.
 4. In an ignition system for a rotary internal combustion engine including an ignition switch, an ignition coil having a primary winding and a secondary winding, a breaker connected to the primary winding of the ignition coil, a spark plug for normally igniting a combustible air-fuel mixture in each consecutive compression chamber of the engine, a distributor for selectively connecting the secondary winding of the ignition coil to the spark plug to cause the production of spark at the spark plug to be incident to the opening of the breaker, and cams driven by the engine for opening the breaker, the improvement comprising an electromechanical switch meMber connected between the ignition coil and the breaker and responsive to certain decelerating and idling conditions of engine for controlling the firing of the spark plug to produce a spark in alternate compression cycles, in which the electromechanical switch member for controlling the firing of the spark plug comprises a normally closed switch connected between the ignition coil and the ignition switch, the switch being opened in response to engine decleration, an auxiliary breaker connected in parallel with the switch, and a cam driven by the engine for opening the auxiliary breaker in alternate openings of the breaker, in which the cam for opening the breaker is a cam having two opposed lobes, and the cam for opening the auxiliary breaker is a cam having a single lobe, the single lobe being angularly aligned with the opposed lobes of the breaker cam. 